According to Symantec’s report, Boston’s problems come from an especially high concentration of “spam zombies” — computers taken over by outside hackers to send out spam.

Another factor is the Hub’s many unsecured WiFi hotspots — 53.6 per 100,000 residents – where cyber criminals may lurk, trolling for unwitting users. While high-profile or widespread computer attacks are relatively rare, small-scale attacks like these threaten even savvy computer users, the report noted.